Hey Yogi, thanks for your post. I've actually been working on this quietly for a bit now, more as a personal hobby project than anything. For my initial version, here's what I'm shooting for:
- Each of the 4 outputs are channel selectable. Regardless of input channel.
- Volume setting or offset per channel. So you could set the output volume of CH1 to 127 (max), or you could increase it by a factor. Maybe a percentage of the original volume, or by a constant. That way dynamics may still work.
- Pitch Offset. This will probably be a percentage. Almost like a pitch wheel but more fixed.
- As cheap as possible. I'm hoping for $50 including a semi-decent case.
- Actually purchasable. Seems like most devices like this are harder to buy, like the two you posted. No PM'ing people on forums.
Everything is/will be released as free and open source under GPLv2. If you or other want to add your own features, that will totally be supported! And contributions back to the "official" firmware would be nice!
I've actually lost a bit of steam on this, so your post has kind of reignited my spark a bit. Let me know if you have any questions.